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[Brad Figg <brad.figg@xxxxxxxxxxxxx>]

This bug is missing log files that will aid in diagnosing the problem.
>From a terminal window please run:

apport-collect 1239109

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable
to run this command, please add a comment stating that fact and change
the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the
Ubuntu Kernel Team.

** Changed in: linux (Ubuntu)
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1239109

Title:
  aarch64 clock_gettime with CLOCK_REALTIME_COARSE or
  CLOCK_MONOTONIC_COARSE fails with SIGBUS or SIGSEGV

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  The aarch64 vDSO __kernel_clock_gettime implementation crashes when
  clock_gettime is called with CLOCK_MONOTONIC_COARSE or
  CLOCK_REALTIME_COARSE, with a SIGSEGV or SIGBUS respectively.

  In the implementation
  (http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/kernel/vdso/gettimeofday.S#n89)
  a value other than CLOCK_REALTIME or CLOCK_MONOTONIC branches past the
  usual "mov x2, x30" which preserves lr for return later. Anything
  other than CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE then
  branches directly to the svc call, which correctly returns to the
  caller. But CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE execute
  the special coarse path then fall through to the normal
  CLOCK_REALTIME/CLOCK_MONOTONIC path, which does a 'ret x2' at the end,
  despite not having saved x30 to x2 in the _COARSE case. So it ends up
  setting pc to clk_id, which is either 4 or 5, giving a translation or
  alignment fault.

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